1. Field of the Invention
The present invention relates generally to patterned nanostructures, and more particularly to patterned functional nanostructures.
2. Description of the Prior Art
Marine organisms like diatoms and radiolaria provide many examples of intricately organized architectures preserved in silica or calcium carbonate. Such natural microstructures are formed by biomineralization, a templated self-assembly process in which preorganized organic surfaces regulate the nucleation, growth, morphology and orientation of inorganic crystals. To date, a variety of synthetic pathways that mimic aspects of biomineralization have been explored to prepare patterned ceramic materials.
Hierarchical materials assembly strategies have been developed which allowed growing surfactant-templated mesoporous silica in solution route on hydrophobic patterns prepared by micro-contact printing (μCP). The films formed by this technique are usually noncontinuous and have globular morphologies. In addition it takes days to form nanostructures using μCP. Oriented mesoporous silica patterns, using a micro-molding in capillary (MIMIC) technique can be made. However, it requires hours to form such ordered structures under electric field.
Although progress has been made in the preparation of a wide variety of patterned ceramic materials, current synthetic methods have several inherent drawbacks from the standpoint of nanotechnology: First, most templating procedures are conducted in time-consuming batch operations often employing hydrothermal processing conditions. Second, the resultant products are typically ill-defined powders, precluding their general use in thin film technologies. Third, procedures developed to date are often limited to forming patterns of pores.
For many envisioned nanotechnologies, it would be desirable to create patterned nanocomposites consisting of periodic arrangements of two or more dissimilar materials. None of the existing technologies provide a means to fulfill the above need.
Soft lithography approaches have been combined with surfactant and particulate templating procedures to create oxides with multiple levels of structural order. However, materials thus formed have been limited primarily to oxides with no specific functionality, whereas for many of the envisioned applications of hierarchical materials, it is necessary to define both form and function on several length scales. In addition the patterning strategies employed thus far require hours or even days for completion.
Such a long processing time is not very useful in further developing nanotechnologies because slow processes are inherently difficult to implement in commercial environments. Hence a rapid method that enables one to form hierarchically organized structures on substrates in a matter of seconds is highly desirable.